algovoi-rfc9421-verifier (Python)

AlgoVoi-authored reference verifier for RFC 9421 (HTTP Message Signatures) plus RFC 9530 (Digest Fields for HTTP). Python and TypeScript, byte-for-byte parity, Apache 2.0.

What it does

• Verify an incoming RFC 9421-signed HTTP request against a known public key.
• Re-validate a captured request after it traverses a TLS-re-terminating proxy chain (the property pinned in the rfc9421_proxy_chain_v0 conformance fixture).
• Build conformance test harnesses anchored to the RFC 8032 Section 7.1 deterministic Ed25519 reference keypair.

This package verifies HTTP message signatures (RFC 9421 + RFC 9530): the wire-level signing-base reconstruction, the Content-Digest check, and the Ed25519 signature check against a supplied public key. That is a different surface from the AlgoVoi JCS RFC 8785 receipt-body discipline. HTTP signature verification (this package) and receipt-content verification (the AlgoVoi receipt-format packages) are complementary: this verifier confirms wire-level message integrity; the JCS substrate confirms receipt-body canonical integrity.

Verification options

verify_request applies hardening on top of the signature check. Verifying the signature alone does not make an authentic request safe; these arguments enforce freshness, coverage, and algorithm policy:

• required_components — reject unless every listed component (e.g. @method, @authority, @path) is covered by the signature (closes request-line-rewrite gaps).
• require_content_digest (default True) — require content-digest to be a covered component and verify it against the body (no body-swap).
• allowed_algorithms (default {"ed25519"}) — algorithm allow-list; an absent alg is always rejected.
• now, max_age_seconds, max_skew_seconds, require_created, enforce_expires — freshness window; only signed created / expires are trusted.
• nonce_seen — single-use nonce store probe (nonce, keyid) -> seen, checked after the signature verifies; fails closed on a store error.
• expected_tag / require_tag — enforce the RFC 9421 tag (anti cross-protocol reuse).

Always on: non-canonical, off-curve, and small-order Ed25519 public keys are rejected before verification, and the Signature value must be canonical base64.

from algovoi_rfc9421_verifier import verify_request

result = verify_request(
    method="POST", authority="api.example", path="/pay",
    headers=headers, body=body, public_key=pubkey_hex,
    required_components=["@method", "@authority", "@path"],
    require_created=True, max_age_seconds=300,
    nonce_seen=store.seen,
)
if not result.valid:
    ...  # deny

Install

pip install algovoi-rfc9421-verifier

License

Apache 2.0. See LICENSE.